Automatic coffee maker and switch therefor



April 17, 1956 1. J. KUESER AUTOMATIC COFFEE MAKER AND SWITCH THEREFOR 2 Sheets-Sheet l Filed April 14, 1951 fyi/92721017 Jozz J zefez" @fm awww 997%@ April 17, 1956 J. J, KUESERv 2,741,975

AUTOMATIC COFFEE MAKER AND SWITCH THEREFOR Filed April 14, 1951 2 Sheets-Sheet 2 IUI/@afar J /zzefer 5M, 972mm y 30a zzyo:

United States Patent AUTOMATIC COFFEE MAKER AND SWITCH THEREFOR Application April 14, 1951, Serial No. 221,056 6 Claims. (Cl. 99-281) My invention relates to an improved automatic coffee maker of the vaculator type characterized by the ability to execute one coffee making cycle when the upper bowl is placed in assembled position on the lower bowl and to keep the coffee at a suitable warm temperature suitable for consumption at all other times.

Coffee makers of the vaculator type utilize a lower bowl or pot having an annular lip or surface which receives the mating gasket carried by the upper bowl to form an air tight connection. The upper bowl has a riser tube which, when the bowls are assembled, extends down into the lower bowl to a point adjacent the bottom thereof. in coffee making operations, coffee grounds are placed in the upper bowl and water in the lower bowl. The lower bowl is then heated to boil the water therein and drive it up the riser tube into the upper bowl where it extracts the essence from the coffee grounds. When the water is boiled out, or nearly so, heating is discontinued, allowing steam in the lower bowl to condense and draw the water, now containing the coffee essence, back into the lower bowl. In automatic coffee makers it is common to provide thermostatic control means to keep the coffee infusion thus made at a warm serving temperature after its return to the lower bowl.

In one type of automatic coffee maker of the vaculator type, the heater is energized to boil the water by suitably moving a manually operated conditioning switch, such as a detent element located at the base of the lower bowl. This initiates the high heat condition of the heater which continues until the water is driven to the upper bowl, at which time the high heat is automatically interrupted. Vvhen the coffee infusion then returns to the lower bowl, the temperature is maintained indefinitely in the coffee warming range by a suitable on-off thermostatic switch operative independently of the conditioning switch or its detent or similar operating element.

This type of automatic coffee maker has provenhighly satisfactory in operation and has received considerable success for domestic use. However, it does require a small degree of control since the high heat condition will beA created and maintained indefinitely if the manually operated setting switch is set to the coffee-making condition when the upper bowl of the coffee maker is not in place.

In accordance with the present invention even this possibility of misoperation of the coffee maker is prevented by the use of automatic switch elements sensitive to the presence of the upper bowl on the colee maker in coaction with a thermostatic operating mechanism that automatically resets itself without the use of a manually operated element. With this structure, the user merely ,removes the upper bowl from the coffee maker when the infusion has been made and returned to the lower bowl, a step required to pour the coffee in any event, and thereafter is assured of the fact that the heater will operate on the keep warm condition over, the unit so operates even though the user disconnects the coffee maker and at some time thereafter reconnects 1t to warm the infusion.

without furtherattention. t Moreto the upper-bowl 10 to define 2,741,975 Patented Apr. 17, 1956 Moreover, in the structure of the present invention the coffee maker is automatically switched to the desired conditions of coffee making or keep warm by the positioning of the upper bowl which is inherently required in arranging the apparatus for operation and no manually operated switch elements of any kind are required.

It is therefore a general object of the present invention to provide an improved automatic vaculator type coffee maker which cannot be accidentally reset to operate on the high heat condition.

Another object of the present invention is to provide an automatic vaculator type colee maker involving no manually setting switch elements.

Further it is an object of the present inventionto provide an automatic vaculator type coffee maker including ele- Still another object of the present invention is to pro-l vide a wide band thermostatic switch suitable for use in a vaculator type coffee maker.

Further it is an object of the present invention to provide a vaculator type coffee maker with means sensitive to the assembled condition of the upper and lower bowls and yet does not interfere with normal coffee making operations or with the attractive appearance of the unit..

The novel features which I believe to bev characteristic of my invention are set forth with pended claims. to its construction and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

Figure l is a view in elevation of a vaculator type coffee maker constructed in accordance with the present invention;

Figure 2 is an enlarged fragmentary broken-away view of the engaging handles and switch structure of the coffee maker of Figure 1;

Figure 3 is a view like Figure 2 but of a modified form -of the switch structure;

.type coffee maker. The lower bowl has an outwardly extending flared lip portion, indicated at annular seat which receives the rubber 12a, defining an gasket 14 secured a tight seal in the assembled condition. The riser tube 10a, formed as part of the upper bowl, extends down through this seal as shown.

The lower bowl 12 is received upon and attached to the stand 16 which defines a protective electrically insulating skirt 16a and a plurality of heat insulating support legs 161;. This stand forms an enclosure for the heater and thermostatic operating elements described hereafter.

The upper bowl 10 may be handled and detached from the lower bowl by the use of handle 10b which is of Bakelite (phenol-formaldehyde condensation product) or similarheating insulating material. A handle 12b of like material permits lifting the lower bowl 12 and pouring coffee'therefrom. A suitable spout or pouring lip (not shown) is provided on the lip 12a to facilitate pouring.

ln accordance with one form of the present invention the handle 12b of the lower bowl has a cavity 18, Figure particularity in the ap- My invention itself, however, both as When the detent.isreleased',` itlifts'under"the-biasof'spring d to separate disk-20!)y andthe' contacts Zll'a'andthereby break 'the'circuiL "The detent 20c is 'held inthe `handle 12b for shiftin g up 4'and down'movements by the' bearing opening 20e and is held against removalwfronthecavity 18 bythe disk TZ'Ob'which `abuts the bottom `face ""o'f the bearing sleeve ZGe-When'the' detent is'released."

Preferably the handle'f12bhas anarcuate' "bore 12e to receive connecting wires extending'from 'thestandl to the switchlto'deiine the electric circuitsrlestiribetlherejk The temperature responsivefcontrol"switchrneclranism is best vseeninl thefcrossesectional -viewof VFigure 4'which shows thefbottorn 1'2d`of thelower bowl 12. As shown, a nearly circular heatingfelement 22 is secu'edto the bottom 12d by soldering on other -suitable means for ntimate-thermal relationftherewith. The heatingielement may, Ifor example; consist of atube of ycopper or brasscontainin-g'an argillaceous till carrying a heater coil of'resistance wire having-length and'cross-section ycapal'ile' 4off producing the required heat for coffee making when connected/to thelusua'l domestic electric supply. L'Such'elements 'are well known 1 inv the art -and'-formy no part of the present invention.

Ther-bottom -12d also carries a heat conducting support` bracket 24, likewisesoldered or otherwise secured in position forintimateheat'contact.'- This bracket extends downwardly Vfrom the bottom and receives the screws 24a 'which anchorthe two'bimetallic blades', 26 aud28, to the conducting bracket 24V so4 that these blades partake of and respond to the temperatureof the lower bowl12.y When heated, these blades hex outwardly from the center ofl-they bottom '12d'to' positions such as shownin" the dotted lines, Figure 4.

The blade26 coactsy with the resilient switch arm Z7 to form a narrow-band on-.oif switch to maintain the lower bowlv at a preset'keep-warm temperature.H To this end, arnif27- isfcarried by the bracket 27a formedby the skirt portion of stand 16 in position to be engaged bythe bimetallcblade v`26. At its free end the arm 27 .carries contact-button 27b"wh'ich, when arm`27 is released, bottoms against the'corre-sponding contact button 30b. ofarm 30 toestablish a'circuit connection.. .Arn1l30 isresilient and is vsupported from' the base lof stand 16 by the bracket 30a.

The positonof arm `30 isadjustably tixedbythe vset screw"32 which is threadedlyreceived by the bracket'Za ofthe base '16. This screw xes the A,position of the-bimetallic blade 26 at whiclrthecontact :buttons 27b and 301; touch and thereby establishes the temperaturefvalue maintained by the'.thermostatic switch defined by blade 26 and arms 27 and 30.

The thermostatic blade '28 forms the actuating element of the wide band .coffee making'ther-mostatic .switch indicated generally at 34..'and shown in :perspective view in Figures Tand 8. f `This switch. includes a pair. ofzresilient blades .34a Aand 3411 .held in sandwiched position .fbythe insulating-spacers34Cl which vin turn are 'pressed against each other by the .screws 34d. The support arm "36- is also sandwiched-between the spacers .34e a-nd at its remote end is' attaChedto-:and supported by;1the'bracketportion 36a.of:xthebase '16. Thisattachment isachieved `by the screws :Sb which are threadedlyere'ceived'bythe-bracket portion 36a.

.The 'screws @34d fare threadedly receivedbyth'eiblade 34e which extends outboard of spacers 34e to be engaged by set screw 38 a-s is'described in further detail hereafter. A compression spring 35, which may, for example, be a U-shaped leaf spring, bottoms at its opposite ends on the arms 34a and 34b as shown. Since this spring urges these arms to opposed flexed positions (except in the practically unimportant dead center position), the arms 34a and 34b are positively driven to opposed flexed positions Arm 34b is provided with a contact button 34f which engages the contact button 40a of the relatively inllexible arm 40 to establish a circuit connection when arms 34a and "34`b are in the positions shown-in Figure 4 and Yto'break that connection when the arms are in the opposed position.

The :arm 34a extends outboard of. arm 34h toiform a face against which the insulating button 28a of blade 28 bears. As the blade 2S is heatedl to flex towards the right as seen in Figure 4, the button 28a bears against arm 34a until the latter is driven over dead center, at which time the arms 34a and=-34b are driven tothe opposite over-center or flexed positions to break contact between buttons 34j and 40a.

' Ait-extension or'outrigger 28b is also carried by the blade 28 and threadedly receives the screw 42 which Vhas an insulating washer v42a carried `by its head portion. This vwasher is of sufficient diameter to overlay the path of travel of theouter reaches of the arm 34a as shown, thus straddling arm 34a `in conjunction with button 28a. T-hewasher 42a engages the blade 34a to force it back overf-centerto restore the positionsof Figure 4'when the bimetal 28 has cooled suiciently to exert the torque requisiteifor. this purpose.

'The set screw 38 is threadedly carried by a bracket 38a inthe base 16.

r The heaterZZ is energized from the appliance cord ter minals 44 through either of two circuits. Onecircuit, the keep 'warmvrcircui may be traced directly to the heater through the contact buttons 27h and 30h, this circuit passingthrongh conductors 46, 48, and 50. 'The other circuit,

'theircofee'making circuit, may be -tracedto the heater throughthe `switch 20 andthe contact buttons 34j and 40a inv. series, this .circuit `passing through conductors 52, 54,56, 48, and 50.

, Operation with the required .amount of water, the upper bowl.10

placed in position, and. the necessary coilee placed in the upper bowl, .a .suitable strainer being provided r to .hold the cbfee groundsagainst passage .through therisertube 10a.' The switch .elements then-have the positions ofFigure 4 for the switch 20 is closed by the presence4 ofthe upper bowl 10 and the bimetallic .blades 26 and .28 .being in'wthe 'low .temperature positions where contacts 34f -40a and27b4-.30'b are closed.

When theappliance cord is then plugged in, the heater 22 is energized through both-contacts 34f-40a and 27b 30b.and the lower .bowl 12 accordingly heated. As this heating Continues, the lower bowl 12..rises to a temperature' above the keep warm temperature (which may, for example, be "i F.) atwhichtime the contacts 27hy 30h separate. This does. not alterthe heater operation irlcedthe circuit throughcontacts 34f-40a remains estab- As 'the heatingcontinues furthenthe temperature in the 'lower bowl 12- ,rises to boiling .temperature and remains at that value until nearly all the water is driven to the upper bowl where it. comes intocontact withthe coffee grounds. and removes the essencetherefrom to:make.the coieel infusion. "The .temperatuIeo-the bottom` of .the loweribowl rises as the water isdrivenfrom it, thus .causing the bimetal blade2g to llexto theposition `of .Figure 6', where it drives the arm 34a overcenter to cause spring 35'tosw1ng arms 34a and 34b to the :opposite positions of ilexure as shown in Figure 6. Contact button 34f accordingly swings to spaced position in relation to button 40a, thus interrupting the energizing circuit to heater 22.

When power to the heater 22 is interrupted by the action of the arms 34a and 34b as they swing over center, the lower bowl 12 cools and the steam therein condenses to create a vacuum drawing the coffee infusion back into the lower bowl. The cooling thereafter continues until eventually the keep-warm temperature (say 180 F.) is reached and the bimetallic blade 26 relaxes suiliciently to relieve arm 27 to permit engagement of contacts 27b and 30b as shown by the dotted lines of Figure 6. The heater is then intermittently energized under the control of the thermostatic switch formed by arms 27 and 30 and by the bimetallic blade 26 to maintain the brew at the selected keep-wann temperature.

The thermostatic switch 34 remains in the open circuit position of Figure 6 while the lower bowl 12 is at the keep-warm temperature because the bimetallic blade 23 at this temperature does not move sufficiently to cause the disk 42a to drive arm 34a back over dead center. This condition is shown in Figure 5.

In the ordinary and usual coffee making operation, the upper bowl 16 is removed when the brew returns to the lower bowl 12 and the coffee is poured from the lower bowl either immediately or within a reasonably short time. The conditions described above accordingly continue until the coffee is consumed. However, if the coffee is not to be consumed for some time, the appliance cord connected to prongs 44 may be disconnected for reasons of economy and safety, thereby deenergizing the unit completely and permitting the lower bowl 12 to cool below the keep-warm temperature to a lower value and eventually to room temperature. When the temperature falls to a value of, say 135 F., the bimetallic blade 28 unflexes sufliciently to force the arm 34a over center, thus causing arms 34a and 34h to reverse positions to the initial positions shown at Figure 4. Even in this condition, however, the circuit through the contacts 34f-40a to the heater 22 is interrupted by switch 20 which is open because the upper bowl is removed. Consequently, the heater 22 is operated only under the control of bimetal 26 to maintain the keep-warm temperature when the appliance cord is again connected. There is accordingly no tendency of the unit to recycle under the high heat or colee making control of bimetal 28.

It will be noted that the thermostat switch defined by blade 28, arms 34a and 34b, and the spring 35 is a wide band thermostatic switch in that the temperature range between the high temperature at which it changes to the olf position and the lower temperature at which it restores the on position is relatively large. For example, in a practical coffee maker this switch may open the circuit at 220 F. and subsequently reclose the circuit at 135 F., the former temperature being indicative of the fact that the water is substantially expelled from the lower bowl 12 and the latter being below the keep-warm temperature but above room temperature.

The value of the high temperature at which the bimetal 28 moves arms 34a and 34b to the off position is determined by the adjustment of the set screw 38a which xes the position of the blade 28 corresponding to dead center of the arm 34a. The value of the low temperature at which the bimetal 28 restores arms 34a and 34h to their low temperature positions is determined by the adjustment of set screw 42 which controls the position of the blade 28 at which the arm 34a is driven to dead center by engagement with the disk 42a.

The thermostatic switch defined by bimetallic blade 26 and arms 27 and 30 is a narrow band thermostatic switch having the smallest temperature difference between the on and oi positions consistent with economic construction, reliability, and reasonably low cycling frequency in order to maintain the brew at as nearly constant temperature as pssiblf The value of the temperature so regulated is determined by the adjustment of set screw 32.

Figure 3 is a view like FigureV 2 showing an alternative form of the switch 20 utilizing magnetic attraction for actuation. In this structure the handle 12b has a cavity 118 in which are disposed the iixed contacts 120a and the magnetic armature 120d, the latter connected by post 120C to the conducting disk 120f which engages contacts 120a when the armature 120d is in the up position. The armature 120:1 registers with a permanent magnet 120e mounted in the handle 10b of the upper bowl 10 so that when the upper bowl is in position, the armature is lifted and the circuit across contacts 124m established. When the upper bowl is not in position, the armature is no longer attracted and drops to break the circuit.

It will be observed that the structure of Figure 4 is like that of Figure 2 in that it forms a normally open switch that senses the fact that the upper bowl is in position and then closes. Moreover, like the structure of Figure 2, it does not interfere with the seal between the bowls 10 and 12 achieved by the gasket 14.

Figures 7 and 8 are perspective views of the wide-band switch unit. As shown, blade 34a has an elongated opening in which the blade 34b tits so as to avoid interference and the spring 35 is rockably anchored to these arms by end openings which receive protuberances on the blades.

While l have shown specic embodiments of my invention, it will of course be understood that other structures may be used without departing from the true spirit and scope thereof. l therefore intend by the appended claims to cover all modifications and alternative constructions falling within their true spirit and scope.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An automatic colee maker comprising in combination, a lower bowl having an annular seating surface, an open upper bowl adapted to seat on said surface and having a riser tube extending into the lower bowl when in assembled relation therewith, a heater for the lower bowl, a wide band thermostatic switch responsive to the temperature of the lower bowl operative to open above colee warming temperature and to close below coiee warming temperature, a normally open switch, means defining an energizing circuit to the heater through said switches in series, said last switch being carried by one of said bowls, and interengaging parts carried on the upper bowl and the lower bowl cooperating to close the said last switch when the bowls are in assembled relation.

2. An automatic cotee maker comprising in combination, a lower bowl having an annular seating surface, an open upper bowl adapted to seat on said surface and having a riser tube extending into the lower bowl when in assembled relation therewith, a heater for the lower bowl, a wide band thermostatic switch responsive to the temperature of the lower bowl operative to open above coffee warming temperature and to close below coffee warming temperature, a normally open switch, means defining an energizing circuit to the heater through said switches in series, said last switch being carried by one of said bowls, interengaging parts carried on the upper bowl and the lower bowl cooperating to close the said last switch when the bowls are in assembled relation, a narrow band thermostatic switch responsive to the temperature of the lower bowl and operative at coffee warming temperature, and means defining a circuit to the heater through the narrow band switch independently of said first circuit to maintain the coffee at warming temperature.

3. An automatic coffee maker comprising in combination a lower bowl having an annular seating surface, an open upper bowl adapted to lit on said surface and having a riser tube extending into the lower bowl when in assembled relation therewith, a heater for the lower bowl, a wide band thermostatic switch responsive to the temperature of the lower bowl operative to open above coffee warming temperature and to close below coffee warming 7 temperature, an energizing circuit tof. the heater throughA Asaid switches in ,-series,l :said rbowlsuhaving handles,- `said-last1-switch being .mounted onv the vhandle ofthe lowerbowl andeng'ageable by the handle ofthe upper bowL to close @when theibowlssare in assembled relation.

r 4. An automaticfcofree maker comprisingingcombination, a lower vbowl havingan annularfseating surfaceyan opennpper bowl .adapted to seat onsaid surface; and having afriser'tube extending intov the lowerbowl when. in

assembled relation therewith, a heater for the lower bowl, awide band'thermostatic switch responsive. to the ternperatureof the flowerbowlv operative .to'open above coffee warming temperature and to close-belowe'coifee warming temperature, a normally open switchgmeans deiining :an

energizing Lcircuitto the heater through said switches in seriessaidrbowls ha-Vinghandlessaid last Aswitch being mountedonthe handle of the lower bowl andy engageablc by thefhandlez-of the upper'bowlfto close Vwhen the bowls are-,in `assembled relation, a narrowband thermostatic switch responsive to the tempera-ture of the lower'bo'wl and operative at coiee warming temperature, and'means defining a circuit to the heater through the narrow lband switch independently of said rst circuitv to maintain the coiee at warming temperature.

i 5.l An automatic coifee maker comprising iny combination, a lower bowl having an annular' seating surface, an open yupper bowl adapted to seat on said Surface and'having a riser tube extending into the lower bowl when in assembled relation therewith, a heaterfor the 'lower bowl;

affwide band thermostatic switch responsive to the temperature of the lowcr'bowl operative to-open above colee warming temperature and to cle-se below coee warming temperature, a normally operr switch having a magnetic actuatingpart, and means delining an energizing circuit to the Vheater through said switches in series, the magnetic actuating'part of lsaid normally open switch being mounted on thelower bowl, and magnetic elements on the upper bowl coopera-ble with vthe magnetic 'actuating vpart 'of the normally open switch to close the same when the bowls" areiin assembled relation.

a normally openswitch, andmeans deijning assembled;V relation` therewith, a heater `for the lowerfbowl,

a wideband thermostatic switch responsive to the temper ature-'of the Slowerfbowl operative to. open vabove coffee warming-temperature -and'to close belowfcolee warming temperature; a-normally--open switch having a magnetic actuating-part;randmeansdening an energizing circuit to the heaterthrough'said switches in series,itheA magnetic actuating -part of said'normally open'switch-being mounted onthe lower bowl, magnetic elements on the rupper bowl cooperable with the magnetic actuating part of the normally open switch toclose the same vwhen the bowls'are in assembled relation, and means dening a circuit to the heater throughthe narrow band .switch independently of said first circuit to maintain thel coffeeat warming temperature.

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